Overview and aims. This book is intended as a self-contained guide to the entire ?eld of bioinformatics, interpreted as the application of information science to - ology. There is strong underlying belief that information is a profound concept underlying biology, and familiarity with the concepts of information should make it possible to gain many important new insights into biology. In other words, the vision underpinning this book goes beyond the narrow interpretation of bioinf- matics sometimes encountered, which may con?ne itself to speci?c tasks such as the attempted identi?cation of genes in a DNA sequence. Organization and features. The chapters are grouped into three parts, cov- ing the relevant fundamentals of information science, overviewing all of biology, and surveying applications. Thus Part I (fundamentals) carefully explains what - formation is, and discusses attributes such as value and quality, and its multiple signi?cations of accuracy, meaning, and effect. The transmission of information through channels is described. Brief summaries of the necessary elements of set theory, combinatorics, probability, likelihood, clustering, and pattern recognition are given. Conceptssuch as randomness,complexity,systems and networks,needed fortheunderstandingofbiologicalorganization,arealso discussed. PartII(biology) covers both organismal (ontogeny and phylogeny,as well as genome structure) and molecular aspects. Part III (applications) is devoted to the most important prac- cal applications of bioinformatics, notably gene identi?cation, transcriptomics, p- teomics, interactomics (dealing with networks of interactions), and metabolomics.